Typically, rolling element bearings are used in rotating machinery designs (e.g. liquid rocket engine turbopumps) to provide radial and axial support of a rotating shaft assembly. These rolling element bearings are often a single ball bearing or a pair of preloaded angular contact ball bearings. The bearings are typically mounted to the rotating shaft and provide axial and radial positional control of the shaft.
One method of obtaining adequate radial and axial load carrying capabilities with some amount of damping is to use a combination of preloaded angular contact ball bearings and a hydrodynamic bearing. Yet many designs, including turbopumps for rocket engine applications, typically incorporate a balance piston to control the axial position of the shaft at various operating speeds. The balance piston utilizes the controlled pressures in a fluid flow circuit to provide axial thrust of the shaft while balancing the loads applied to the turbine. However, the angular contact ball bearings only control the axial position of the rotor during start-up and shut-down conditions. At operating speed, the axial position of the shaft is controlled by the balance piston, as noted above. The amount of axial movement of the shaft is considerable and the design requires that the outer race of the bearing assembly be slidably fitted in the bearing support housing.
A hydrodynamic bearing may center the shaft at operating speeds, potentially eliminating contact of the bearing outer race with the bearing support housing. In the absence of contact, the bearing outer race will spin and potentially gall as the race intermittently contacts the bearing housing. This spinning and galling of the bearing outer race can lead to part failure.
Accordingly, it would be highly desirable to provide a mechanism for preventing this failure by implementing a bearing cup rotational locking assembly that allows for significant shaft axial travel while preventing rotational movement of the outer race of the bearings.